#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {

   int i,t;
   scanf("%d",&t);
    
    for(i=0;i<t;i++)
    {
        int n,j,flag=0;
        scanf("%d",&n);
        int arr[n][2];
        int a,b,max_x=0,max_y=0,min_x=1000000,min_y=100000000;
        for(j=0;j<n;j++)
        {
            
            scanf("%d %d",&a,&b);
            arr[j][0]=a;
            arr[j][1]=b;
            if(a>max_x)
                max_x=a;
            if(a<min_x)
                min_x=a;
            if(b>max_y)
                max_y=b;
            if(b<min_y)
                min_y=b;
        }   
        int side;

        for(j=0;j<n;j++)
        {
        
            if(arr[j][0]==min_x && arr[j][1]>=min_y && arr[j][1]<=max_y)
            {}
            else if(arr[j][1]==min_y && arr[j][0]>=min_x && arr[j][0]<=max_x)
            {}
            else if(arr[j][0]>=min_x && arr[j][0]<=max_x && (arr[j][1]==min_y || arr[j][1]==max_y))
            {}
            else if(arr[j][1]>=min_y && arr[j][1]<=max_y && (arr[j][0]==min_x ||arr[j][0]==max_x))
            {}
            else
                flag =1;
        }    
        if(flag ==1)
            printf("NO\n");
        else
            printf("YES\n");
    }    
   
    
    return 0;
}